Periodic Table

Periodic table is the arrangement of chemical elements and they are organized according to their atomic numbers and electronic configurations. By the time 1800 there were only 31 elements which were discovered. After fifty years later by 1850, scientists had discovered more chemical elements which were 63 in numbers and the numbers kept increasing. With the discovery and study of more elements and their compounds, the various data about them also increased. It became progressively difficult to organise all the known elements but different scientists made attempts to look for some trends and patterns in their property. Firstly the elements were classified as metals and non-metals only but later, there were some elements which were neither classified as metal or non-metal, as they possessed different properties which later got the name metalloids. As this kind of classification was insufficient for systematic studies of the elements and their compounds, several scientists attempted to make a rational and systematic classification of the physical and chemical properties of elements and showed it into a form of a table. Such tables helped even to predict the new elements, opening new insights into understanding the properties of the matter. Thus, periodic classification of elements evolved.

Newlands' Law of Octaves

In 1866, John Alexander Newland arranged the elements in the increasing order of their atomic masses and noticed that every eighth element has properties similar to the first element. It was then called as Newland Law of Octaves because the relationship was just like every eighth, not that resembles the first in octaves of music. Newlands' Law of Octaves seemed to be working only for elements up to calcium and later after calcium the law of octaves could not work on periodic table.

Lothar Meyer's Atomic Volume Curve

In 1864, scientist Lothar Meyer formed chart in which he plotted various physical properties as a function of their atomic masses. The atomic volumes were calculated by dividing atomic masses by the solid state density of the elements. Conclusion which was drawn by Lothar Meyer's curve:-a) The alkali metals (Li, Na, K, Rb, and Cs) occupy the peaks on the curve.b) The alkaline earth metals (Be, Mg, Ca, Sr, and Ba) and the elements forming basic oxides occupy the descending position on the curve.c) The halogens (F, Cl, Br, I) and the elements forming acidic oxides occupy the ascending position on the curve.